(a) Field of the Invention
The present invention relate to a method of manufacturing a semiconductor device. More particularly, the present invention relates to a method of manufacturing a semiconductor device that removes residues of polymer remaining in a trench for a metal line.
(b) Description of the Related Art
Typically, a semiconductor device has a plurality of layers sequentially formed on a substrate. In such a multi-layered structure, an interlayer insulation layer such as an oxide layer is required for insulation between layers, and a metal line may be formed in each layer.
Accordingly, metal lines (i.e., upper and lower metal lines) of adjacent metal layers having an interlayer insulation layer therebetween may be electrically connected with each other through a via hole formed through the interlayer insulation layer.
According to a conventional method, a lower metal line is firstly formed, and then a thick interlayer insulation layer is formed thereon. In addition, for an electrical connection between the lower metal line and an upper metal line that will be formed on the interlayer insulation layer, a photoresist pattern is formed on the interlayer insulation layer, for example, through a photomask process (application of a photoresist, exposure, development, etc.). Then, a via hole or a trench that selectively exposes an upper surface of the lower metal line may be formed by an etching process using the photoresist pattern.
For example, as shown in FIG. 1, a via hole 104 and a trench 106 are formed in a semiconductor substrate 102 (typically using separate photolithography steps for the trench and via). Here, the uppermost portion of the semiconductor substrate 102 includes the interlayer insulation layer (such as an oxide layer). When the via hole 104 and the trench 106 are formed, the photoresist pattern and residues of the etching process (for example, a carbon-based polymer) are removed through a dry ashing process (for example, an O2 ashing process), a solvent cleaning process, etc.
When the oxide layer is etched using a photoresist pattern to form the trench 106, residues such as a polymer may remain in the trench 106. As a result, a crown defect 108 caused by the polymer may occur, as shown in FIG. 1. Such a polymer formed in the trench during the etching process of the oxide layer may not be fully removed easily by a dry ashing process or a solvent cleaning process, and it frequently remains in the trench.
However, a crown defect formed in the trench may be a cause of degradation of electrical characteristics of a metal material that will be filled in the via hole and the trench. In this case, the reliability and productivity of the semiconductor device may deteriorate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form prior art or other knowledge that is already known in this or any other country to a person of ordinary skill in the art.